aboutsummaryrefslogtreecommitdiffstats
path: root/source/Plugins/LanguageRuntime/CPlusPlus/CPPLanguageRuntime.cpp
blob: b392282c3eb1a846284530e238ebaf0501567234 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
//===-- CPPLanguageRuntime.cpp
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include <string.h>

#include <memory>

#include "CPPLanguageRuntime.h"

#include "llvm/ADT/StringRef.h"

#include "lldb/Symbol/Block.h"
#include "lldb/Symbol/Variable.h"
#include "lldb/Symbol/VariableList.h"

#include "lldb/Core/PluginManager.h"
#include "lldb/Core/UniqueCStringMap.h"
#include "lldb/Symbol/ClangASTContext.h"
#include "lldb/Target/ABI.h"
#include "lldb/Target/ExecutionContext.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/SectionLoadList.h"
#include "lldb/Target/StackFrame.h"
#include "lldb/Target/ThreadPlanRunToAddress.h"
#include "lldb/Target/ThreadPlanStepInRange.h"

using namespace lldb;
using namespace lldb_private;

static ConstString g_this = ConstString("this");

char CPPLanguageRuntime::ID = 0;

// Destructor
CPPLanguageRuntime::~CPPLanguageRuntime() {}

CPPLanguageRuntime::CPPLanguageRuntime(Process *process)
    : LanguageRuntime(process) {}

bool CPPLanguageRuntime::IsWhitelistedRuntimeValue(ConstString name) {
  return name == g_this;
}

bool CPPLanguageRuntime::GetObjectDescription(Stream &str,
                                              ValueObject &object) {
  // C++ has no generic way to do this.
  return false;
}

bool CPPLanguageRuntime::GetObjectDescription(
    Stream &str, Value &value, ExecutionContextScope *exe_scope) {
  // C++ has no generic way to do this.
  return false;
}

CPPLanguageRuntime::LibCppStdFunctionCallableInfo
CPPLanguageRuntime::FindLibCppStdFunctionCallableInfo(
    lldb::ValueObjectSP &valobj_sp) {
  LibCppStdFunctionCallableInfo optional_info;

  if (!valobj_sp)
    return optional_info;

  // Member __f_ has type __base*, the contents of which will hold:
  // 1) a vtable entry which may hold type information needed to discover the
  //    lambda being called
  // 2) possibly hold a pointer to the callable object
  // e.g.
  //
  // (lldb) frame var -R  f_display
  // (std::__1::function<void (int)>) f_display = {
  //  __buf_ = {
  //  …
  // }
  //  __f_ = 0x00007ffeefbffa00
  // }
  // (lldb) memory read -fA 0x00007ffeefbffa00
  // 0x7ffeefbffa00: ... `vtable for std::__1::__function::__func<void (*) ...
  // 0x7ffeefbffa08: ... `print_num(int) at std_function_cppreference_exam ...
  //
  // We will be handling five cases below, std::function is wrapping:
  //
  // 1) a lambda we know at compile time. We will obtain the name of the lambda
  //    from the first template pameter from __func's vtable. We will look up
  //    the lambda's operator()() and obtain the line table entry.
  // 2) a lambda we know at runtime. A pointer to the lambdas __invoke method
  //    will be stored after the vtable. We will obtain the lambdas name from
  //    this entry and lookup operator()() and obtain the line table entry.
  // 3) a callable object via operator()(). We will obtain the name of the
  //    object from the first template parameter from __func's vtable. We will
  //    look up the objectc operator()() and obtain the line table entry.
  // 4) a member function. A pointer to the function will stored after the
  //    we will obtain the name from this pointer.
  // 5) a free function. A pointer to the function will stored after the vtable
  //    we will obtain the name from this pointer.
  ValueObjectSP member__f_(
      valobj_sp->GetChildMemberWithName(ConstString("__f_"), true));

  if (member__f_) {
    ValueObjectSP sub_member__f_(
       member__f_->GetChildMemberWithName(ConstString("__f_"), true));

    if (sub_member__f_)
        member__f_ = sub_member__f_;
  }

  lldb::addr_t member__f_pointer_value = member__f_->GetValueAsUnsigned(0);

  optional_info.member__f_pointer_value = member__f_pointer_value;

  ExecutionContext exe_ctx(valobj_sp->GetExecutionContextRef());
  Process *process = exe_ctx.GetProcessPtr();

  if (process == nullptr)
    return optional_info;

  uint32_t address_size = process->GetAddressByteSize();
  Status status;

  // First item pointed to by __f_ should be the pointer to the vtable for
  // a __base object.
  lldb::addr_t vtable_address =
      process->ReadPointerFromMemory(member__f_pointer_value, status);

  if (status.Fail())
    return optional_info;

  lldb::addr_t address_after_vtable = member__f_pointer_value + address_size;
  // As commened above we may not have a function pointer but if we do we will
  // need it.
  lldb::addr_t possible_function_address =
      process->ReadPointerFromMemory(address_after_vtable, status);

  if (status.Fail())
    return optional_info;

  Target &target = process->GetTarget();

  if (target.GetSectionLoadList().IsEmpty())
    return optional_info;

  Address vtable_addr_resolved;
  SymbolContext sc;
  Symbol *symbol;

  if (!target.GetSectionLoadList().ResolveLoadAddress(vtable_address,
                                                      vtable_addr_resolved))
    return optional_info;

  target.GetImages().ResolveSymbolContextForAddress(
      vtable_addr_resolved, eSymbolContextEverything, sc);
  symbol = sc.symbol;

  if (symbol == nullptr)
    return optional_info;

  llvm::StringRef vtable_name(symbol->GetName().GetCString());
  bool found_expected_start_string =
      vtable_name.startswith("vtable for std::__1::__function::__func<");

  if (!found_expected_start_string)
    return optional_info;

  // Given case 1 or 3 we have a vtable name, we are want to extract the first
  // template parameter
  //
  //  ... __func<main::$_0, std::__1::allocator<main::$_0> ...
  //             ^^^^^^^^^
  //
  // We do this by find the first < and , and extracting in between.
  //
  // This covers the case of the lambda known at compile time.
  size_t first_open_angle_bracket = vtable_name.find('<') + 1;
  size_t first_comma = vtable_name.find(',');

  llvm::StringRef first_template_parameter =
      vtable_name.slice(first_open_angle_bracket, first_comma);

  Address function_address_resolved;

  // Setup for cases 2, 4 and 5 we have a pointer to a function after the
  // vtable. We will use a process of elimination to drop through each case
  // and obtain the data we need.
  if (target.GetSectionLoadList().ResolveLoadAddress(
          possible_function_address, function_address_resolved)) {
    target.GetImages().ResolveSymbolContextForAddress(
        function_address_resolved, eSymbolContextEverything, sc);
    symbol = sc.symbol;
  }

  auto get_name = [&first_template_parameter, &symbol]() {
    // Given case 1:
    //
    //    main::$_0
    //
    // we want to append ::operator()()
    if (first_template_parameter.contains("$_"))
      return llvm::Regex::escape(first_template_parameter.str()) +
             R"(::operator\(\)\(.*\))";

    if (symbol != nullptr &&
        symbol->GetName().GetStringRef().contains("__invoke")) {

      llvm::StringRef symbol_name = symbol->GetName().GetStringRef();
      size_t pos2 = symbol_name.find_last_of(':');

      // Given case 2:
      //
      //    main::$_1::__invoke(...)
      //
      // We want to slice off __invoke(...) and append operator()()
      std::string lambda_operator =
          llvm::Regex::escape(symbol_name.slice(0, pos2 + 1).str()) +
          R"(operator\(\)\(.*\))";

      return lambda_operator;
    }

    // Case 3
    return first_template_parameter.str() + R"(::operator\(\)\(.*\))";
    ;
  };

  std::string func_to_match = get_name();

  SymbolContextList scl;

  target.GetImages().FindSymbolsMatchingRegExAndType(
      RegularExpression{R"(^)" + func_to_match}, eSymbolTypeAny, scl, true);

  // Case 1,2 or 3
  if (scl.GetSize() >= 1) {
    SymbolContext sc2 = scl[0];

    AddressRange range;
    sc2.GetAddressRange(eSymbolContextEverything, 0, false, range);

    Address address = range.GetBaseAddress();

    Address addr;
    if (target.ResolveLoadAddress(address.GetCallableLoadAddress(&target),
                                  addr)) {
      LineEntry line_entry;
      addr.CalculateSymbolContextLineEntry(line_entry);

      if (first_template_parameter.contains("$_") ||
          (symbol != nullptr &&
           symbol->GetName().GetStringRef().contains("__invoke"))) {
        // Case 1 and 2
        optional_info.callable_case = LibCppStdFunctionCallableCase::Lambda;
      } else {
        // Case 3
        optional_info.callable_case =
            LibCppStdFunctionCallableCase::CallableObject;
      }

      optional_info.callable_symbol = *symbol;
      optional_info.callable_line_entry = line_entry;
      optional_info.callable_address = addr;
      return optional_info;
    }
  }

  // Case 4 or 5
  if (symbol && !symbol->GetName().GetStringRef().startswith("vtable for")) {
    optional_info.callable_case =
        LibCppStdFunctionCallableCase::FreeOrMemberFunction;
    optional_info.callable_address = function_address_resolved;
    optional_info.callable_symbol = *symbol;

    return optional_info;
  }

  return optional_info;
}

lldb::ThreadPlanSP
CPPLanguageRuntime::GetStepThroughTrampolinePlan(Thread &thread,
                                                 bool stop_others) {
  ThreadPlanSP ret_plan_sp;

  lldb::addr_t curr_pc = thread.GetRegisterContext()->GetPC();

  TargetSP target_sp(thread.CalculateTarget());

  if (target_sp->GetSectionLoadList().IsEmpty())
    return ret_plan_sp;

  Address pc_addr_resolved;
  SymbolContext sc;
  Symbol *symbol;

  if (!target_sp->GetSectionLoadList().ResolveLoadAddress(curr_pc,
                                                          pc_addr_resolved))
    return ret_plan_sp;

  target_sp->GetImages().ResolveSymbolContextForAddress(
      pc_addr_resolved, eSymbolContextEverything, sc);
  symbol = sc.symbol;

  if (symbol == nullptr)
    return ret_plan_sp;

  llvm::StringRef function_name(symbol->GetName().GetCString());

  // Handling the case where we are attempting to step into std::function.
  // The behavior will be that we will attempt to obtain the wrapped
  // callable via FindLibCppStdFunctionCallableInfo() and if we find it we
  // will return a ThreadPlanRunToAddress to the callable. Therefore we will
  // step into the wrapped callable.
  //
  bool found_expected_start_string =
      function_name.startswith("std::__1::function<");

  if (!found_expected_start_string)
    return ret_plan_sp;

  AddressRange range_of_curr_func;
  sc.GetAddressRange(eSymbolContextEverything, 0, false, range_of_curr_func);

  StackFrameSP frame = thread.GetStackFrameAtIndex(0);

  if (frame) {
    ValueObjectSP value_sp = frame->FindVariable(g_this);

    CPPLanguageRuntime::LibCppStdFunctionCallableInfo callable_info =
        FindLibCppStdFunctionCallableInfo(value_sp);

    if (callable_info.callable_case != LibCppStdFunctionCallableCase::Invalid &&
        value_sp->GetValueIsValid()) {
      // We found the std::function wrapped callable and we have its address.
      // We now create a ThreadPlan to run to the callable.
      ret_plan_sp = std::make_shared<ThreadPlanRunToAddress>(
          thread, callable_info.callable_address, stop_others);
      return ret_plan_sp;
    } else {
      // We are in std::function but we could not obtain the callable.
      // We create a ThreadPlan to keep stepping through using the address range
      // of the current function.
      ret_plan_sp = std::make_shared<ThreadPlanStepInRange>(
          thread, range_of_curr_func, sc, eOnlyThisThread, eLazyBoolYes,
          eLazyBoolYes);
      return ret_plan_sp;
    }
  }

  return ret_plan_sp;
}